Histopathological characteristics of non-alcoholic fatty liver disease in children: Comparison with adult cases

Aim: Non‐alcoholic steatohepatitis (NASH) has been classified pathologically into type 1 (characterized by ballooning and perisinusoidal fibrosis) and type 2 (characterized by portal inflammation and portal fibrosis). Reportedly, type 2 NASH has been the most commonly observed histopathological feature in pediatric non‐alcoholic fatty liver disease (NAFLD). While only a few studies have documented the histopathology of pediatric NAFLD so far, appropriate histopathological classification or characteristics of pediatric NAFLD, and the disease incidence correlation with race or ethnicity are still controversial. Methods: In this study, we compared the clinical and histopathological characteristics of NAFLD in 34 pediatric and 23 adult cases. Results: We found that pediatric steatosis was more severe than adult steatosis. Perisinusoidal fibrosis was significantly milder in pediatric cases than in adult cases. Lobular inflammation and ballooning was found to be milder in pediatric cases than in adult cases. On the other hand, portal inflammation was more severe in pediatric cases than in adult cases. The so‐called borderline zone 1 NASH, similar to type 2 NASH, was observed in 21% of pediatric subjects; this rate was more than twice that in adult subjects. Fifty percent of pediatric cases showed overlapping features of types 1 and 2 NASH. Intralobular and portal changes showed positive and significant correlations with each other. Serum aminotransferase levels reflected the histopathological severity of NAFLD. Conclusion: We confirmed that pediatric NAFLD exhibits histopathological features that are different from adult NAFLD. The classification consisting of “type 1 NASH” and “type 2 NASH” may be impractical.